AIDS Conference Cites Breakthroughs

Activist protests about access to, and the price of, AIDS medicines marked the International AIDS conference in Barcelona. But they failed to overshadow the promising results of research into new ways of attacking the virus.

Switzerland-based Roche and its research partner, the US biotech company Trimeris, gave details of its trials on T-20, the first in a new class of antiviral agents called fusion inhibitors. In contrast to current treatments, which prevent the virus from replicating once it is inside the cell, the new agents prevent the virus from entering cells in the first place. In one trial, 37 percent of patients showed no sign of the virus after 24 weeks, compared with 16 percent of those on existing therapies. In a second trial, the figures were 28 percent and 14 percent, respectively. Roche hopes to launch the medicine in the first quarter of 2003.

A joint venture between Shionogi and GlaxoSmithKline reported the results of its first human study on a product in another new class, one which targets integrase, one of three enzymes HIV needs for replication. Marketed medicines already target the other two, reverse transcriptase and protease. Phase I trials showed the treatment was well tolerated, with headache the most common side effect, and Phase II trials are now under way in HIV-positive individuals.

Panacos Pharmaceuticals is investigating a third new approach. Preclinical trials showed that its candidate, PA-457, inhibits budding, the final stage of the AIDS virus' takeover of human cells, when it releases virus particles to invade the body. The company plans to start clinical trials sometime next year.

Vaccines, rather than medicines, are likely to provide the ultimate "cure" for AIDS. VaxGen has one in development, with two trials underway. The first, conducted in the United States, Canada, and the Netherlands, involves 5,400 patients at high risk of sexual transmission. The second with, 2,500 drug users, is underway in Thailand. Based on the virus' protein coating, the vaccine is designed to stimulate HIV-blocking antibodies.